Hydrothorax in a case of heartwater

Abstract

After being bitten by an infected tick E. ruminantium enters the animal in the saliva of the tick. Initial multiplication of the parasiteprobably takes place in cells of the lymph node regional to the tick bite from where it enters the blood stream and invades endothelial cells in various tissues and organs. Increased vascular permeability resuylts in transudation of fluid into various body tissues (e.g. brain and lungs) and body cavities (e.g. pericardial and thoracic cavities), but the precise mechanisms responsible for the transudation are poorly understood. Pathology: the lesions in cattle, sheep and goats are similar, the most pronounced being often severe hydropericardium, hydrothorax and lung oedema with serofibrinous foam being present in the bronchi and trachea. These images illustrated a severe case. (Source: Allsopp, BA, Bezuidenhout, JD & Prozesky, L 2004, 'Heartwater', in Coetzer, JAW & Tustin, RC, Infectious diseases of livestock, Cape Town, Oxford University Press, 2004)